Power unit cooling device

Abstract

A centrifugal fan is mounted to an inner plate of a centrifugal clutch as a heat-generating rotating device, and an intake port of a casing is formed near a front side in the axial direction of the centrifugal fan. The centrifugal fan includes a base plate connected to the inner plate of the centrifugal clutch, plural fins formed on the base plate, blow-off holes each formed between arbitrary adjacent fins and extending axially through the base plate, and guide walls for guiding a radially outward air flow over the base plate into the blow-off holes. Air just after admitted from the intake port passes through the blow-off holes and is blown against the centrifugal clutch.

1. A power unit cooling device for a power unit having a power source and a power transmission mechanism disposed within a casing of the power unit, comprising:
 a centrifugal fan having a front side and a rear side, disposed within the casing and configured so that air introduced from the front side of the centrifugal fan is allowed to flow through an interior of the casing by a blow-off action of the centrifugal fan; 
 wherein the centrifugal fan is mounted on a rotary shaft of a heat generating rotating device that generates heat during operation; 
 a flow dividing mechanism connected to the centrifugal fan for dividing a part of an air flow to be blown off radially outwardly and a part of an air flow to be blown off axially towards the rear side of the centrifugal fan; and 
 the centrifugal fan includes: 
 a base plate integrally connected to the rotary shaft of the heat-generating rotating device; 
 a plurality of fins on an outer periphery edge portion of the base plate; 
 a blow-off hole penetrating axially through the base plate between a pair of adjacent fins; and 
 a guide wall disposed between the adjacent fins to conduct air flowing radially outward over the base plate into the blow-off hole; 
 wherein the heat generating rotating device is a centrifugal clutch that transmits a rotating power to an outer rotor that is connected to a driven side of the clutch when the number of revolutions of an inner rotor connected to the power source has reached a predetermined number of revolutions; 
 wherein the centrifugal clutch includes an inlet port for conducting air blown-off axially towards the rear side of the centrifugal fan into an interior of the centrifugal clutch; and a discharge port for discharging the air from the interior of the centrifugal clutch to an exterior of the centrifugal clutch; 
 wherein the centrifugal clutch is interposed between an input side of the power transmission mechanism, which is for transmitting engine power to a driving wheel, and an engine crank shaft the centrifugal fan being mounted on an input side of the centrifugal clutch, and wherein the air blown off radially outward by the centrifugal fan is fed to the interior of the casing, while the air flowing axially backward as a divided air flow from the centrifugal fan is fed to the interior of the centrifugal clutch. 
 
     
     
       2. A power unit cooling device according to  claim 1 , wherein the power transmission mechanism is a belt type continuously variable transmission. 
     
     
       3. A power unit cooling device for a motor vehicle, comprising:
 a casing configured to house a heat generating rotating device, wherein the heat generating rotating device includes a rotary shaft; 
 a centrifugal fan disposed within the casing wherein the centrifugal fan includes: 
 a base plate connected to the rotary shaft of the heat-generating rotating device; 
 a plurality of fins disposed on an outer periphery edge portion of the base plate; 
 a blow-off hole penetrating axially through the base plate between a pair of adjacent fins; and 
 a means for directing air flow from a front side of the fan radially outward over the base plate and axially through the blow-off hole, wherein the means is connected to the front side of the fan and disposed between the pair of adjacent fins; 
 wherein the heat generating rotating device is a centrifugal clutch that transmits a rotating power to an outer rotor that is connected to a driven side of the centrifugal clutch when a number of revolutions of an inner rotor connected to a power source has reached a predetermined number of revolutions; 
 wherein the centrifugal clutch is interposed between an engine crank shaft and an input side of a transmission, wherein the centrifugal fan is mounted on an input side of the centrifugal clutch such that air directed radially is fed to an interior of die casing while air directed axially is fed to an interior of the centrifugal clutch. 
 
     
     
       4. A power unit cooling device according to  claim 3 , wherein the transmission is a belt type continuously variable transmission.